There are a variety of solar energy collectors available for converting solar energy into other forms of energy that can be more readily used or stored. These apparatuses typically employ solar collectors that collect solar radiation and convert it into a more useable form of energy, such as heat.
Solar collectors of the flat plate type have been used in low energy applications such as heating water, generating low pressure steam, supplementing air conditioning and heating systems, and the like. Flat plate collectors do not focus the sun's radiation and have limited applicability.
Another type of collector is generically called a concentrating collector. These collectors focus or concentrate the sun's radiation energy in a particular area. Concentrating collectors can be designed to operate at high temperatures with reasonable flow rates, thus substantially increasing the versatility over apparatuses employing flat plate collectors.
One type of concentrating collector is the parabolic trough collector. This type of collector uses an elongated reflective trough having a parabolic cross-section to concentrate the sun's radiation along a focal line extending through the focal points of the parabolic elements of the trough. A conduit can be positioned along this focal line and a heat transfer liquid can be circulated through the conduit, where it will be heated by the sun's energy. Satisfactory flow rates at high temperatures can be obtained from these collectors. With the assistance of a tracking system, parabolic trough collectors can become very efficient as they follow the movement of the sun.
Parabolic type collectors are efficient and versatile for generating energy from solar radiation. As solar energy collector apparatuses incorporating parabolic type collectors are used to satisfy larger energy requirements, they become physically larger. In some apparatuses, the aggregate collector surface may typically approach thousands of square meters. Consequently, there is a need for light-weight parabolic type collectors so that they are easier to transport and assemble.
U.S. Pat. No. 4,4234,719 discloses a parabolic trough solar energy collector that is fabricated without the need for any blind fasteners or blind fastening devices. A integrated parabolic solar energy collector is provided which can be welded or fastened with spot welds, seam welds, rivets, bolts or the like.
U.S. Pat. No. 4,135,493 discloses a parabolic trough solar energy collector including an elongated support with a plurality of ribs secured thereto and extending outwardly therefrom. One surface of the ribs is shaped to define a parabola and is adapted to receive and support a thin reflecting sheet which forms a parabolic trough reflecting surface. One or more of the collectors is adapted to be joined end to end and supported for joint rotation to track the sun.
Even in view of the advances made in parabolic trough solar energy collectors, there is still a need to simplify their construction so that they are easier to transport and assemble.